There are numerous inventions relating to fluid conveying members or conduits, and various coupling devices that can be used to interconnect fluid conveying members. The particular design of the coupling device, as well as the design of the fluid conveying members is typically determined by the special requirements associated with the type of fluid being conveyed. For conveying non-volatile fluids such as water, a coupling device may be afforded a more simple construction, since potential leakage in many applications may not introduce a significant health or safety concern. On the contrary, for fluid conveying members that convey fuel or other volatile or hazardous liquids, the construction of the coupling device and fluid conveying members typically requires redundant sealing features, as well as redundant locking or tamper proofing features.
For fluid conveying members that convey fuel that are used within particularly hazardous applications such as within an aircraft, stringent industry standards have been developed to ensure safety in the handling of fuel. Any leakage of fuel within such an environment could result in a catastrophic fire or explosion.
Fluid conveying members in aircraft are typically connected to one another with robust and reliable couplers that ensure a leak proof seal is achieved between the connected fluid conveying members. The abutting ends of the fluid conveying members include a metallic flange that is received within and held by the coupler. The metallic flange is often attached to the end of the fluid conveying tube by a swaging process in which the flange or tube is swaged, and therefore a fluid tight seal is achieved between the flange and tube end.
One example of a reference that discloses a swaged fitting includes the U.S. Pat. No. 5,452,921. The fitting is used in an attachment to a tube comprising a cylindrical sleeve having a tapered outer surface and an inner surface for receiving the tube. A cylindrical swaging ring having a tapered inner surface engages the tapered outer surface of the sleeve such that axial movement of the ring in a forward direction with respect to the sleeve causes the ring to apply a radial force to the sleeve to swage it to the tube. The swaging ring is locked onto the sleeve both before and after swaging by one or more protrusions on the outer surface of the sleeve which cooperatively engage an annular groove in the swaging ring.
Another example of a reference that discloses a swaged configuration for tubing and an associated sleeve or flange includes the U.S. Pat. No. 3,730,567. Specifically, a coupling sleeve for a swaged attachment to tubing is disclosed. The sleeve has a pair of annular grooves of a predetermined depth provided in the inner peripheral wall with the grooves being separated by an annular ring raised from the floor of the grooves. The width of the annular ring in the axial direction is such that tubing swaged into the grooves tends to assume a separate bend adjacent each land edge and to remain essentially flat in the area intermediate the two edges. The inner diameter of the cylindrical body in the area of the annular ring is arranged such that it is less than the inner diameter of the body in the area of the annular grooves and greater than the inner diameter of the cylindrical body in the area remote from the grooves thereby resulting in a two stage application of force to the tube walls during the swaged attachment operation.
Another example of a reference that discloses a swaged connection for tubing and an associated coupling device includes the U.S. Pat. No. 7,900,976. The device includes a coupling body and a collar adapted to engage a tubular member in a permanent swaged connection. The coupling device includes axially spaced front and back ferrules that engage during swaging to provide a plurality of seals intermediate the ferrules and the tubular member as well as the coupling body. The back ferrule includes a central region having a generally cylindrical wall that is elastically deformed to a corrugated tube-like shape during swaging to enhance the maintenance of the seals. A portable installation tool for swaging the coupling body and collar to the tubular member is hydraulically actuated.
With respect to a swaged connection between a fluid conveying member such as a tube/pipe and a corresponding flange/ferrule, there are generally two types of swaging processes. Internal swaging is a process by which the internal member (the tube/pipe) is internally expanded to compress the tube/pipe material against the interior surface of the corresponding flange/ferrule. Such internal swaging can be achieved by pulling a hardened tool of a larger diameter through the interior of the tube/pipe in order to expand it against the interior surface of the flange/ferrule. External swaging is a swaging process in which the outer flange/ferrule is compressed onto the interior tube/pipe. External swaging can be achieved by pushing the components to be joined through a hardened die having an interior diameter smaller than the external diameter of the flange/ferrule. In both cases, the compressive force applied to the components causes material to flow into the serrated cavities, thus providing a secure mechanical bond that is leak proof.
Although swaging is known to be a reliable method of joining a flange and tube for purposes of conveying hazardous fluids, quality control checks must still be made in order to confirm that a swaging process has been successful in creating a leak proof connection. The current practice used for quality control involves destructive testing of a statistical sampling of swaged connections. Specifically, swaged samples or “coupons” are cross-sectioned to analyze the joint or connection to determine the quality of the swaged connection. Since this destructive sampling is only done on a statistical basis, there is still the potential for fluid conveying members to be used in which a swaged connection may not be entirely adequate for the intended use.
Because of the inherent disadvantages of statistical sampling and destructive testing, there is a need to provide the capability to confirm the adequacy of a swaged connection, especially for those environments in which volatile fluids are conveyed. There is also a need to provide such capability without significantly altering the construction of the fluid conveying line, flange, or coupling device. There is yet further a need to provide such capability that is easily confirmed by a user or inspector, without the need for special inspecting equipment.